A porous tube suitable for use as a vascular graft prosthesis and a method of making it is disclosed. It has a structure of porous polytetrafluoroethylene having a fibrous structure of nodes and fibers connecting the nodes together and an integrated intrawall circumferential support adjacent to areas of variable porosity. This invention provides a polytetrafluoroethylene polymer in a porous form useful as artificial internal organs for, for example vascular bypass, vascular access, and endovascular prosthesis. PTFE walls are found with radial zones of differing porosity are described.